Development of novel spectroscopic methods for laser-induced dynamic structural change of protein molecules

为了发展激光诱导蛋白质分子动态结构变化的方法，我们进行了泵浦-倾倒-荧光测量和红外辐射效应观察的实验研究。PYP(光活性蛋白)被选为目标样本蛋白，因为它在触发光脉冲的照射下表现出一个光学循环，导致其结构变化。此外，我们还进行了蛋白质晶体的太赫兹光谱和PYP模型化合物的合成和评价。Pump-Dump-荧光测量显示了PYP的光学反应，观察到这是由触发光引起的结构变化的光学循环。为了研究反应的初始阶段，我们使用了泵浦-倾倒-荧光光谱，并与时间分辨荧光光谱进行了比较，后者使我们能够通过自发发光来追踪激发态的动力学。在倾倒过程中，激发态布居I…更多的S通过受激发射过程倾倒，倾倒效率预计与自发辐射成正比。然而，包括对转储强度饱和效应的详细评估表明，在较长波长区域存在转储效率的提高。这一结果表明，通过控制泵浦和倾倒脉冲光波来控制倾倒过程是有可能的。在红外波长范围内(3μ到6μ)，考察了红外辐照效应的观测。采用自制的光学参量放大器产生的飞秒红外脉冲和由光学参量振荡器产生的纳秒光脉冲进行触发。观察到6μ的红外光脉冲增强了PYP的光学反应。虽然观察到触发脉冲和红外脉冲的一致照射可以增强这种效应，但为了获得明确的证据，实验上的改进仍在继续，以量化这种效应。太赫兹光谱学我们构建了一个反射型太赫兹光谱系统，并应用于观察溶菌酶蛋白质晶体的低频模式。首次成功地实现了蛋白质晶体的太赫兹光谱。观察到的光谱形状依赖于晶体的湿度，与拉曼散射光谱的结果一致。较少

In order to develop methods for the laser-induced dynamic structural change of protein molecules, we performed the experimental studies of pump-dump-fluorescence measurements and the observation of IR irradiation effect. PYP (photoactive protein) was selected as a target sample protein because it showed an optical cycle leading to its structural change by the irradiation of a triggering light pulse. Furthermore, THz spectroscopy for protein crystals and the synthesis and evaluation of model compounds for PYP were also performed.Pump-dump-fluorescence measurementsPYP exhibits an optical reaction which is observed as the optical cycle with structural change induced by triggering light. In order to investigate the initial stage of the reaction, pump-dump-fluorescence spectroscopy was employed and compared to time resolved fluorescence spectroscopy which enabled us to trace the excited state dynamics through spontaneous emission of light. In the dump process, the excited state population i … More s dumped by stimulated emission process and the dump efficiency was expected to be proportional to the spontaneous emission. However, the detailed evaluation including that for the saturation effect of the dump intensity clarified that the enhancement of the dump efficiency in the longer wavelength regions existed. This result suggested the potential for controllability of the dump process by controlling the pump-and dump pulse light wave.Observation of IR irradiation effectIR light pulse irradiation effect on the optical cycle of PYP was examined for the IR wavelength region (3μ to 6μ). The femtoseconds IR pulses which were created by a hand-made optical parametric amplifier were applied while Nanoseconds light pulses generated by optical parametric oscillator were used for triggering. The 6 μ IR light pulses was observed to enhance the optical reaction in PYP. Although coincident irradiation of the triggering pulses and the IR pulses were observed to enhance the effect, in order to obtain clear evidence, experimental improvements are continuing for quantifying the effect.THz spectroscopyWe constructed a reflection-type THz spectroscopic system and applied to observe the low-frequency modes of protein crystals of lysozyme. The THz spectroscopy for a protein crystal was succeeded for the first time. Observed spectral shapes depending on the humidity of the crystal were in accordance with the results obtained by Raman scattering spectroscopy. Less